Tyre Derived Aggregate offers a stable sub-base, whilst SmartMIX gives a longer lasting roadway
In May 2022, Liberty Tire Recycling participated in a Michigan EGLE grant project with Clare County and Michigan Technological University using Tyre Derived Aggregate (TDA) in a base layer of the roadway, and SmartMIX rubber as an additive for the hot mix surface layer. The TDA was used in a section of the roadway with a swamp on both sides – providing a base layer that will not heave and shove due to winter freezing.
The SmartMIX was injected into the Reclaimed Asphalt Pavement (RAP) stream at the mix plant using a blower machine, which makes it very easy for the contractor to handle. SmartMIX helps prevent cracking in the pavement and provides more flexibility and durability in asphalt mixes. Tyre rubber is very well designed to last a long time and this project put them back to good use. About 32,600 end-of-life tyres were beneficially reused on the Lake Haskell Road project.
SmartMIX technology is a hybrid wet process, where the rubber is reacted with asphalt extender oil in advance of delivery to the asphalt mixing plant. At the mixing plant the rubber is handled like a dry powder, but it is in a saturated surface dry condition. It doesn’t swell up and build viscosity like older technologies. The pre-swelled technology can lead to much higher rubber contents in asphalt mixtures leading to more resilient, longer-life pavements.